Environmental and Population Management (LARGE PAGE - wait to load)

• Depending on the disease and the number of individuals involved, the treatment and/or control of disease may require management and manipulation of the population and/or its environment, or treatment and care of an individual or group of animals (see: Treatment and Care).
• The presence of health or disease depends on the interactions between the host species, the disease-producing agents (living and non-living) and the environment in which they exist (components of which may themselves be agents of disease). A large part of disease prevention and control involves modification of the environment and the population to decrease the interaction between disease-producing agents and the species in which they cause disease.
• Effective environmental and population management for disease prevention and control requires an understanding of the agents causing disease, their interaction with the individual and population of the species they affect, the roles of intermediate hosts and the ways in which the environment may affect both the species and the agents of disease.
• Appropriate strategies for disease prevention and control may vary considerably depending on factors such the species of animal under consideration, the type of disease (e.g. toxic, infectious etc.) and whether or not the animals are free-living.
• Environmental and population management may also be employed for control of animals which are causing, or are perceived to cause, problems such as agricultural damage which may bring them into conflict with human interests. (See: Management of Unwanted or Illegally Held Animals)
• In many cases an integrated management strategy involving the implementation of two or more management practices may be more effective than any one single action.

(B36.4.w4,  B126, B127, J2.24.w1).

• Where disease in wild waterfowl is concerned, manipulation of the population and the environment are most commonly employed to reduce the effect of disease outbreaks. However, treatment and care of individual waterfowl or groups of waterfowl may also be appropriate, for example in the cleaning of birds affected by oiling (Oiling), hook and line injuries (Hook and Line Injuries) or botulism (Avian Botulism).
• In captive waterfowl, the treatment and care of individual birds is employed more commonly, although consideration must also be given as to the role of the population and the environment in the development of the disease, and the potential effect on disease incidence of manipulating these.
• Examples of environmental and population management applicable to the control of waterfowl diseases include:

  • Carcass pick-up to reduce the risk of botulism (Avian Botulism).
  • Parallel rather than serial filling of ponds to reduce the risk of disease transmission between enclosures.
  • Increased water levels to take lead shot (Lead Poisoning) out of the reach of dabbling ducks or swans.
  • Avoiding siting power and telephone lines across known waterfowl flight paths.
  • Hazing waterfowl away from the area of oil spills (Oiling) or other toxins.

• Management actions such as hazing may also be employed in resolving conflicts between waterfowl and human interests. (See Population Control of Birds - General)

(B15, B36.4.w4, B122, B127)

• In zoo and wildlife rehabilitation settings, usually treatment will involve a single bear. However, group control of disease may be required for infectious diseases, including parasite infestations, and environmental management may also be required, particularly for parasite control. 

• Group control of diseases must be considered in zoo settings as well as in commercial and laboratory colonies. It is also relevant when dealing with situations such as multi-rabbit households or rescue centres. 

• Group control of diseases is relevant in multi-ferret households as well as in laboratory and breeding colonies and in rescue centres.

Care and treatment of bonobos is particularly aimed at the individual. For conditions such as respiratory infections (Respiratory Tract Disease in Bonobos), consideration of group care is also important.

• Chapter 4 - B36 Field Manual of Wildlife Diseases - Disease control operations

• Disease due to environmental contamination by toxins such as oil (Oiling) and lead (Lead Poisoning) may be prevented by avoiding environmental contamination and by ensuring that if contamination does occur the toxin involved is removed from the environment.
• Removal of contaminants from the environment if they do not naturally break down in the environment may be both costly and difficult. Prevention of contamination is ideal from the disease-prevention viewpoint. However, many of the substances which act as toxic contaminants and cause disease in animals are deposited in the environment as part of their normal use (e.g. pesticides) and banning their use may not be straightforward.
• Where disease agents such as viruses, bacteria, protozoa or helminths are concerned, contamination of the environment by the agent may be avoided by isolating infected individuals and treating infection to prevent shedding of the agent in host secretions/excretions. This includes routine prophylactic treatment for gastro-intestinal nematodes, which not only reduces the burden in the animals themselves but also reduces contamination of the environment, thereby reducing the risk of infection for other animals. N.B. pathogenic micro-organisms may be able to multiply in the environment.
• Within a collection, an area of ground may be "rested" for a year to allow contamination with helminth parasites and pathogenic micro-organisms which may be shed by the animals maintained in the collection, to be reduced by the natural deaths over the year of the infective stages. This is particularly useful to produce a "clean" area on which juveniles may be reared without being exposed to the parasites or pathogenic micro-organisms.
• Build-up of coccidial oocysts in areas used by captive animals may be diminished by general good husbandry and sanitation, including removal of contaminated feed and litter.
• For macroparasite control a variation on this theme involves alternating the species using a particular area, so that infective stages shed by one species are picked up by a different, non-susceptible species.
• Care must be taken to avoid use of an enclosure by a species which is highly susceptible to a particular disease while after the enclosure is/has been used by another species which carries the disease with mild or no illness. 
  • For example, enclosures used by Procyon lotor - Common Raccoon or bears (Ursidae - Bears (Family)) may be contaminated with Baylisascaris spp. roundworms, which are difficult to remove from the environment and which can cause severe disease (larval migrans) in a wide variety of species.
  • Enclosures used by felines (Felidae - Cats (Family)) may be contaminated with Toxoplasma gondii oocysts and should not then be used for species (e.g. lemurs, marmosets, tamarins, Australasian marsupials) which are highly susceptible to disease caused by this protozoon.

(B20.13.w10, B36, B46, B78, B127)

• The most effective way to prevent lead poisoning (Lead Poisoning) is to prevent the deposition in the environment of lead in forms which may be taken in by waterfowl. In particular, this involves avoiding the use of lead shot for shooting and the use of lead weights by anglers.
• Similarly, problems due to fish hooks, fishing line  (Hook and Line Injuries) and a wide variety of items which may cause harm due to ingestion by or tangling around waterfowl may be avoided if the objects  are disposed of safely rather than being discarded into the environment.
• The most effective way to prevent oiling (Oiling) is to prevent accidental and deliberate release of oil into the environment. If oil is spilled, actions may be taken to reduce its spread and to remove the oil from the environment. Similarly exposure to other toxins such as mercury, selenium, and pesticides (among others) may be reduced by reducing release of these substances into environments used by waterfowl.
• In waterfowl, the most common use of "clean" ground is probably to provide an area on which goslings will not pick up gapeworm (Gapeworm Infection) (particularly Cyathostoma bronchialis); it is recommended that hand-reared goslings be given access to grazing not used by either adult or juvenile waterfowl during the previous year.
• Young waterfowl may be reared on water that is not used by other birds. This may reduce the infection rate of intermediate hosts for e.g. Acanthocephalans (thorny-headed worms), thereby reducing the rate of Acanthocephala Infection of the juvenile waterfowl feeding on the intermediate hosts.
• In controlling parasites picked up from vegetation by grazing species of waterfowl it may be possible to allow the alternate use of the area by non-grazing waterfowl species during which time the level of contamination of the grazing will decrease naturally. However, leaving areas completely free of waterfowl for a period may be preferable as this may allow the level of contamination with other pathogens such as Mycobacterium avium, part of the Mycobacterium avium-intracellulare complex, to decrease (see Avian Tuberculosis).
• In carcass pick-up operations (see below: Carcass Pick-up & Disposal) it is essential to carry carcasses in such a manner as to minimize contamination of the environment e.g. by fluids coming from the carcass.

(J23.16.w3, B11.39.w7, B20.13.w10, B36, B37.x.w1, B127, P13.16)

• Poisonous plants such as yew and oleander not only should be removed from enclosures but also may need to be removed from areas close to enclosures, in order to prevent people from offering the plants to the bears. See: Yew Toxicity in Bears, Oleander Poisoning in Waterfowl and Bears.
• Parasite transmission is reduced by general good hygiene and by regular replacement of bedding. (B407.w18)
• It is difficult to decontaminate an enclosure of ascarid ova (eggs). These survive for several years in the environment and are resistant to drying, freezing, direct exposure to sunlight etc. (B10.48.w43, B22.32.w15, P1.1979.w2) Decontamination is possible by application of direct heat using a flamethrower. However, this can be used only on surfaces which will not be destroyed by heat. For example, it cannot be used on wood or painted surfaces. (B10.48.w43, P1.1979.w2)
  • Note: Ascarid ova are not destroyed by normal cleaning with water and disinfectants. Use of high-pressure water for cleaning increases spread of ascarid ova around the enclosure. (B10.48.w43, B22.32.w15, P1.1979.w2)
  • Treating all bears in an enclosure repeatedly with an anthelmintic highly effective against roundworms, such as ivermectin, orally every two weeks or parenterally every three weeks, may allow eventual elimination of this parasite from an enclosure. (P85.1.w2)
• With mite infections such as Audycoptic Mange in Bears, re-infection may occur from other bears or from the enclosure. (B407.w18) It is important to treat all the bears, not just any individual which appears clinically affected. 
  • Treating bears with an effective parasiticide such as ivermectin while they are in quarantine, before introducing them to a new enclosure, may prevent contamination of the new enclosure. (P85.1.w2)
• Where bears are poisoned deliberately, for example in Florida by bee-keepers, prevention requires education and promotion of other methods of protecting bee hives, such as the use of electric fences. (B419.14.w14)

• Removal of soil substrate has been used in an attempt to control Avian Tuberculosis and Intestinal Coccidiosis in captive Brachylagus idahoensis - Pygmy rabbits. However, this approach is hampered by their need for soil for the female to dig a burrow in which to rear her young. (D372)

• Zinc (galvanised) water or food containers should be removed to prevent Zinc Toxicity. (J195.11.w2)

• Paint containing lead must be removed from any enclosures or items to which primates have access to prevent Lead Poisoning. (B644.5.w5, J569.38.w1)
• Keeping domestic dogs and wild canids such as foxes away from enclosures, stored bedding material, food and environmental enrichment materials is recommended to avoid contamination with Echinococcus spp. and the possibility of subsequent Hydatid cysts in Elephants and Great Apes. (D428.8.2.w8b)

• Preventative Medicine for Mammals

• Picking up and disposing of carcasses may be considered a special instance of preventing or removing contamination.
• When deaths are due to infectious disease or to some types of toxicity, carcasses may be a notable source of infectious organism or toxin for other animals, either directly or via environmental contamination. For example, lead poisoned waterfowl (Lead Poisoning) (and waterfowl killed by shooting with lead shot, but not retrieved) may cause secondary poisoning of the raptors which eat them.
• In any case of Anthrax, proper disposal of intact carcasses by incineration, rendering, or burial, and disinfection with 5% formaldehyde is important to reduce soil contamination. (B88, B336.67.w67, J64.21.w21)
  • To prevent environmental contamination, a post mortem examination should not be performed on animals which have died from anthrax. (B101, B336.67.w67, J64.21.w21)
• In most environments carcasses are usually removed by natural scavenging systems within a short time after death. Carcasses generally become noticeable when they are so numerous as to overload the normal scavenging systems. This is most likely to occur in the event of a mass die-off.
• When possible, carcasses should be disposed of on-site, to reduce the risk of spreading contamination to other sites by transport of carcasses.
• The main methods of carcass disposal are by burning, burying, rendering or composting.

• Burning is often the method of choice, and may involve open burning or the use of fixed or portable incinerators. Air quality (air pollution) regulations may prevent the use of open burning. Smokeless, odourless incinerators are available commercially but are expensive
• Burying must consider factors such as local ground-water circulation and drainage, as well as the potential for later exposure of carcasses. Scavenging may be discouraged by sprinkling carcasses with lime or fuel oil, and carcasses must be covered with at least 3-4ft of soil. A deep, narrow trench suitable for carcass disposal may be dug with a backhoe.
• Composting is often used for the disposal of poultry carcasses. This method of carcass removal requires an adequate supply of suitable litter and straw for the alternate layers in the compost heap, also an appropriate impermeable surface to site the heap and adequate containment. Layers of straw, whole carcasses, manure and water are added to the heap in a 1:1:1.5:0.5 ratio by volume, with the solid components laid down in layers and a third of the water added to each layer. N.B. properly constructed such a compost heap heats rapidly, reaches 145-165°F and reduces soft tissues completely within 14 days.
• Rendering may be used for the disposal of freshly-dead birds. The temperature used should be sufficient for sterilization. There is a risk of transmission of disease by the carcass transported.

(J4.200.w2, B10.3.w18, B32.1.w34, B36.4.w4, B127)

• Carcass pick-up and disposal is considered particularly important in waterfowl disease control operations and for prevention of disease in waterfowl, because of the role of carcasses in the development of Avian Botulism outbreaks. Outbreaks of botulism have been recorded following other events which have killed waterfowl or other birds in botulism-prone areas, and the development of maggots containing Botulinum Toxins has been demonstrated in carcasses of birds dying from collisions with lines crossing a botulism-prone marsh.
• In areas which are prone to botulism (Avian Botulism), it may be advisable to initiate a daily search for carcasses (and removal of any carcasses found) during the period when botulism is most likely to occur. This requires adequate records detailing the earliest and latest dates at which cases of botulism have occurred, so that surveillance may be carried out from 10-15 days before the date of the earliest known case to 10-15 days after the date of the latest known case (B36.38.w38).
• In the case of Avian Cholera, large numbers of the causative bacteria, Pasteurella multocida are released into the environment from dead birds, both in discharges (e.g. nasal discharge) and if the carcass is opened by scavengers. Similarly, carcasses of waterfowl dying from Duck Plague should be collected and incinerated to reduce environmental contamination with Duck Enteritis Virus.
• N.B. carcass pick-up may be relatively inefficient, as birds often hide prior to death and studies have shown that the proportion of waterfowl carcasses found and removed during a search (particularly if hidden under vegetation) may be quite low.

(B15, B36.4.w4, B36.38.w38, B127)

• Anthrax has been reported in bears, including fatal infection. (J64.21.w21) Careful disposal of the carcass is important in any case of Anthrax. (B88, B336.67.w67, J64.21.w21)

• Removal and destruction of carcasses may be used in the control of highly infectious diseases in commercial rabbit colonies. (J64.10.w7)

• Carcasses of rodents killed with rodenticides should be removed to avoid the risk of secondary toxicity such as (Anticoagulant Rodenticide Toxicity in Waterfowl and Lagomorphs (with notes on Hedgehogs and Ferrets)
• Carcasses of birds to which ferrets might gain access should be removed to avoid the risk of Avian Botulism in Waterfowl (with notes on Hedgehogs, Elephants, Bears and Ferrets)

• Necropsy of Mammals (Techniques Overview)
• Burning of Carcasses for Foot-and-Mouth Disease
• Burying of Carcasses for Foot-and-Mouth Disease

• Direct sunlight acts as a sterilizing and drying agent and thereby reduces the levels of pathogens and clearing.
• Sunlight may be used to disinfect impervious surfaces such as concrete and equipment (after cleaning).
• The effect of sunlight on pathogens in the soil can be increased by cultivating/turning the soil to bring different layers of earth to the surface. Harrowing of fields may be used to break up faecal clumps and increase exposure of parasites to sunlight.
• Vegetation clearance may also be used to increase the exposure of soil and pathogens to the sun.

(B32.1.w34, B36)

• It is well recognized that excessive shade in waterfowl enclosures may provide conditions ideal for the survival of pathogenic micro-organisms such as Mycobacterium avium, part of the Mycobacterium avium-intracellulare complex. Removal of shade, e.g. by clearing excessive vegetation such as bushes, and turning of soil to increase exposure to sunlight may be a useful part of prevention of Avian Tuberculosis (see also: Accommodation Design for Birds - Furnishings / Plantings) (P3.1990-1991.w1, B36.8.w8).
• Removing vegetation has also been used to reduce the survival of Pasteurella multocida in a control operation against Avian Cholera in nesting wild eider ducks (B127).

• Direct sunlight allows lagomorphs to synthesise vitamin D, which is important for their calcium metabolism.

• Hypovitaminosis D has occurred in an infant bonobo (Calcium-Vitamin D Metabolism Imbalance). It is important that bonobos and other great apes, particularly infants and juveniles, have access to sunlight (and to artificial UV light when access to the outdoors is not possible). (D391.w2, P86.5.w1)

• --

• Both dry heat and wet heat may be used in cleaning and disinfection to remove pathogens from the environment.
• The temperature reached and the time the temperature is held at this level both affect the efficacy of heat in inactivating infectious agents. Most bacteria (vegetative state, not endospores) and many viruses are rapidly killed at 100 °C. Fifteen minutes at 121 °C are necessary to kill bacterial endospores. As an example of the time/temperature interaction, Foot-and-Mouth Disease Virus is not inactivated by 15 seconds at 95 °C, but is inactivated by three seconds at 148 °C.

• Boiling water or live steam may be used to disinfect items, but must be used directly on the item or (for steam) at close range.
• Heat sterilization in an autoclave is used routinely for the sterilization of surgical instruments to avoid transfer of pathogens between patients and may also be used for the sterilization of other heat-tolerant utensils such as feed bowls.
• The use of hot water increases the efficacy of most chemical disinfectants (see below: Chemical Disinfection).
• The addition of detergent to water increases the efficacy of cleaning and decontamination using boiling water/steam.
• Dry heat in the form of flames is effective if there is direct contact between the flame and the pathogen and is used to a limited extent in the sterilization of surfaces such as concrete and asphalt (blacktop, tarmac).
• Fire is also used for controlled burning, e.g. of heather on grouse moors. One effect of this burning is to reduce the population of infective Trichostrongylus nematode larvae, which are found on the tips of the heather.
• Fire may also be used to dispose of infected materials which cannot easily be disinfected or sterilized, including mite-infested materials (litter, small cage etc). and to burn and remove e.g. bushes which act as habitat for ticks (Argasidae and Ixodidae).
• Fire is also used for the disposal of carcasses (see above: Carcass pick up and disposal).
• Burning may be used as a means of removing large quantities of oil from water (Oiling), although its use must be balanced against the resultant atmospheric pollution (P14.5.w11).

(J56.19.w1, B32.1.w34, B32.14.w19, B109, B126, P14.5.w11)

• Burning may be used to dispose of physical structures, litter etc. as well as carcasses, as part of control operations for diseases such as Duck Plague (B36.14.w14).

• Direct heat from a blowtorch is the only definite way to eliminate Baylisascaris sp. (large roundworm) eggs from an enclosure.
  • The use of a blowtorch is restricted to surfaces which will not be damaged by this application of direct heat.
  • Removal of faeces and spot application of a flamethrower to the site where the faeces were lying, prior to hosing down and disinfecting, should reduce the number of infective ova present.
• See: Baylisascaris Infection in Bears

(B10.48.w43, B407.w18, P1.1979.w2)

• Destruction of carcasses may be used in the control of highly infectious diseases in commercial rabbit colonies. (J64.10.w7)

• Burning of Carcasses for Foot-and-Mouth Disease

• Disinfection may be used to remove disease agents at a site and to prevent mechanical transmission of disease agents to other sites.
• No one disinfectant is ideal for use against all micro-organisms or in all situations. Disinfection requires a suitable disinfectant (e.g. chlorine bleach), containers for prepared disinfectant (e.g. buckets), method of applying disinfectant (stiff-bristle brushes, sprayers, foot baths). N.B.:-

• Disinfection should be seen as an adjunct to removal of animal wastes etc., not as a replacement for general cleaning.
• The efficacy of most disinfectants is greatly reduced by the presence of organic matter - surfaces need to be cleaned before disinfectants are used.
  • Cleaning of a building or area should include dry cleaning to physically remove waste matter, followed by wet cleaning, involving soaking, washing, rinsing and drying. N.B. leaving surfaces wet may allow bacteria to multiple to levels higher than they were before the cleaning started. (D267.V.w5)
  • Washing is most effective if water at 500-800 psi is used; addition of a detergent is helpful. (D267.V.w5)
• Disinfectants require time in which to act.
• Disinfectants generally work better at higher temperatures.
• Disinfectants should be used at the manufacturer's recommended dilution.
• Disinfectants are potentially toxic to animals and may be caustic or corrosive, damaging surfaces. Prior to their use consideration must be given as to their half-life and effect on the environment.
• Following use of a disinfectant, after it has been left for the required time, all disinfected surfaces should be rinsed thoroughly before animals are allowed access to the disinfected area. (D267.V.w5)
• Not all disinfectants are equally effective against all agents. In terms of susceptibility, infectious agents may be roughly grouped as follows:

• Susceptible to most chemical disinfectants: Mycoplasmas, enveloped viruses, gram-positive bacteria, gram-negative bacteria.
• Moderately resistant to chemical disinfectants: Non-enveloped viruses, acid-fast bacteria, Chlamydia, fungal spores.
• Highly resistant to chemical disinfectants: Bacterial endospores, coccidial oocysts.
• Extremely resistant to chemical disinfectants: Prions.

• N.B. where a particular infectious disease agent is known to be present, a disinfectant which is recognized as being effective against that agent should be used.
• For more information on individual disinfectants see:

• Bisphenols (Disinfectant)
• Calcium Oxide (Disinfectant)
• Chlorhexidine (Disinfectant)
• Copper Sulphate (Disinfectant)
• Cresols (Disinfectant)
• Formalin (Disinfectant)
• Hypochlorites (Disinfectant)
• Imidazoles (Disinfectant)
• Iodophors (Disinfectant
• Phenol (Disinfectant)
• Pine Oil (Disinfectant)
• Quaternary Ammonium Compounds (Disinfectant)
• Sodium Hydroxide (Disinfectant)

• Hypochlorites (household bleach) are effective or highly effective against a wide range of infectious agents and may be used as a general disinfectant in most circumstances. They are not effective against coccidial oocysts.
• Household bleach may be used to routinely disinfect birdfeeders to reduce the risk of transmission of diseases such as mycoplasma infection and trichomoniasis (Flagellate Infection) in Birds (B36.11.w11, B36.25.w25).
• In collections, the use of disinfectant footbaths on the way into and out of enclosures may greatly reduce the risk of cross-contamination between enclosures.
• Disinfectants have been used to control disease agents in water, sometimes on a large scale, in the control of e.g. avian cholera, duck plague and anthrax. Soil may be disinfected to kill eggs of parasites. Chemicals may also be also used to control arthropod vectors of disease.

(B21, B36.4.w4, B64.w1, B115.2.w5, B127, D267.V.w5).

• Chlorination of water may be used to inactivate duck enteritis virus (B36.14.w14).
• Disinfectants may be used to decontaminate ground infected with duck enteritis virus by raising pH above pH11 (B36.14.w14).
• Disinfection may be appropriately used to kill Pasteurella multocida bacteria in a wetland where large numbers of birds have died from Avian Cholera in a short time (B36.7.w7).

• Disinfection is not effective for destruction of ascarid ova (Baylisascaris Infection in Bears (Parasitic Disease)). (B10.48.w43, B407.w18, P1.1979.w2)

• Disinfect the premises thoroughly following an outbreak of highly infectious diseases such as Aleutian Disease in Ferrets or  Canine Distemper. (J213.8.w3)

• Preventative Medicine for Mammals (Mammal Husbandry and Management)

• Water may be manipulated in a variety of ways:

• Depth: Increasing, decreasing, fluctuating or holding steady.
• Flow rate.
• Water course manipulation e.g. diverting flow to or away from a particular area.
• Control of nutrients entering the water.

• Water depth and/or flow may be increased to dilute contaminants or pathogens.
• Removal of water, by filling in tree holes and removing artificial containers providing small waterbodies suitable for mosquito larvae habitat, has been used to control disease by reducing the numbers of mosquitoes responsible for transmitting the disease.
• Provision of clean water in troughs, and prevention of the use of mudholes heavily contaminated with droppings and associated pathogenic micro-organisms and/or parasites may be used to reduce disease picked up at contaminated watering sites.

(B36, B127)

• Water plays a large part in the development, transmission or control of a variety of waterfowl diseases, including diseases which may cause large die-offs, such as Avian Botulism, Duck Plague and Avian Cholera.
• Water source: water from a 'clean' source, such as a borehole, or mains water, should not contain pathogenic micro-organisms. It should also be free of larger organisms such as invertebrates which, while acting as a food source, may also be intermediate hosts for e.g. gastro-intestinal parasites.  (e.g. freshwater shrimp Gammarus spp. are intermediate hosts for Acanthocephalans - Acanthocephala Infection, water-fleas Daphnia are intermediate hosts for Echinuria uncinata - Echinuriasis (Acuariasis) (J7.7.w1).
• Within a collection, transmission of water-borne diseases between pens may be prevented by running water in parallel rather than in series, so that water is not flowing from one pen to the next.
• Holding the depth of water steady may assist in avoiding the development of botulism (Avian Botulism), as changes in water level may cause the death of plants and animals which can provide substrate for the growth of Clostridium botulinum. (Accommodation Design for Birds - Water Source & Drainage)
• Water depth may be increased to remove lead shot (Lead Poisoning) on the bottom of a water body from being within reach of the waterfowl using that water. This may be difficult, as a water depth which takes lead out of the reach of dabbling ducks may give a depth ideal for shot to be picked up by swans or by diving ducks.
• Water level may be increased to create a wetland habitat for waterfowl, as an alternative to another habitat from which they are being dispersed as part of a disease control operation (see: Relocation).
• Water level may be decreased to drain a wetland to make the area less attractive to waterfowl and encourage them to leave and go elsewhere as part of a disease control operation (see: Hazing / Dispersal).
• Provision of water sufficient for swimming is very important when species such as seaducks are being held, to avoid the development of disease problems such as Keel Lesions and Bumblefoot.
• For the control of Duck Plague, in which water-borne transmission is very important, within captive populations, swimming water may be removed, with drinking water provided in bowls.
• Increasing water flow and avoidance of still areas in a pond may be used to prevent the build-up of Daphnia (water-fleas) which carry Echinuria uncinata (see: Echinuriasis (Acuariasis)) (B36.35.w35)
• The addition of a large volume of water to an area may be useful to dilute the concentration of Pasteurella multocida in water during an Avian Cholera outbreak (B36.7.w7).
• Avoiding high nutrient loading of water, e.g. by reducing the use of fertilizers and improving sewage treatment and control of animal wastes may reduce the occurrence of algal blooms (B36.36.w36).
• Avoiding flooding of areas which have been dry for a long time, draw-down of water, and fluctuations of water are important in botulism-prone areas, to reduce die-offs of invertebrates or vertebrates which may act as substrates for the growth of Clostridium botulinum (see: Avian Botulism)(B36.38.w38).
• Where possible, monitor and modify pH and salinity of water to avoid the maintenance of conditions recognized as being hazardous for the growth of Clostridium botulinum (B36.38.w38).

(J56.19.w1, B36, B127)

• Ensure bears have access to adequate water for drinking and bathing. 
  • Alopecia and abrasion may be seen due to excessive rubbing in a bear kept in too small an enclosure without an adequate clean water pool for bathing. (B16.9.w9)

• It is important to ensure that clean water is provided.
• Enclosures should be designed to avoid flooding.

• It is important to ensure that clean water is provided at all times.

• It is important to ensure that clean water is provided at all times.

• Accommodation Design for Mammals - Water Source & Drainage
• Accommodation Design for Mammals - Pond / Lake / Watercourse Design, Structure and Maintenance

• Substrates are important both because of the direct affect they may have on animals in contact with them and as a repository of potential pathogens and toxic substances.
• Soil cultivation: may be used to bury hazardous materials such as soybeans (see: soybean impaction), mouldy peanuts (see: aflatoxicosis) and lead shot (Lead Poisoning), and to reduce levels of parasites and other pathogens by exposing soil to direct sunlight (B127).
• Soil tilling may also be used in conjunction with disinfection to remove pathogens (B115.2.w5)
• Enclosures may be rested (allowed to lie fallow) to reduce parasite and other pathogen levels in the soil. This is important in particular for reducing the level of parasite contamination of ground used for juveniles. Many parasites with a direct life cycle (no intermediate hosts) can over-winter in the environment and eggs or larvae produced in young hosts (and adults) one year are present to infect the naïve juveniles of the following year. If ground is rested for a full year, i.e. two enclosures are used in alternate years, parasite burdens may be reduced considerably. (B115.2.w5)
• Substrate may also be manipulated to avoid the development of poached areas in which various pathogens (e.g. bacteria, protozoa) may thrive. This may involve work around the banks of ponds, filling in dips in the ground in small enclosures, re-seeding and encouraging grass growth and avoiding overstocking (see below: Decrease Population Density section on this page).

• Substrates may be modified to remove or cover rough, abrasive surfaces such as concrete and provide surfaces such as earth, grassland, butyl rubber or artificial turf, which are less likely to cause abrasions (see: Bumblefoot).
• Cultivation of earth may be used to bury items such as lead shot (see: Lead Poisoning), soybeans (see: Soybean Impaction) and mouldy peanuts (see: Aflatoxicosis (Mycotoxicosis)), thereby denying waterfowl access to these.
• Soil turnover may also be used to bring different layers of soil to the surface where it may be acted on by sunlight, and therefore the level of pathogenic organisms such as Mycobacterium avium-intracellulare complex decreased (see: Avian Tuberculosis).
• In waterfowl, resting ground is used particularly to avoid Gapeworm Infection in goslings

(B36.8.w8, B36.37.w37, B37.x.w1).

• Easily-cleaned substrates such as concrete may be used in areas where bears regularly defecate. Removing faces properly reduces contamination with ova of gastro-intestinal parasites such as ascarids (See: Baylisascaris Infection in Bears)

• Replacement of soil substrate with rubber flooring has been used in an attempt to control Avian Tuberculosis and Intestinal Coccidiosis in captive Brachylagus idahoensis - Pygmy rabbits. However, this approach is hampered by their need for soil for the female to dig a burrow in which to rear her young. (D372)

• Changing the indoor substrate may be important in controlling dust and maintaining high humidity levels appropriate to minimise the development of Laryngeal Air Sacculitis in Bonobos. (P133.2012.w3)

• Accommodation Design for Mammals - Substrate

• Shelter, along with water and food, is one of the fundamental requirements of all species (J56.19.w1). For animals in captivity it is essential to provide shelter from extremes of ambient temperature and precipitation. Extreme heat, extreme cold and heavy or prolonged precipitation are recognized as potentially important stressors which may have considerable impacts on host immunity, as well as having direct deleterious effects on animals.
• Shade: may be increased to provide shelter from excessive sunlight, thereby reducing the risk of Sunstroke / Heatstroke and sunburn (see: Burns).
• Shelter may be provided in winter to protect animals from cold, with the addition of supplemental heat if appropriate.

(J56.19.w1, B36.6.w6, B100, B131.w1).

• It is important to ensure that an area of the pond or lake is shaded, using an artificial screen (shade-netting) if necessary (B13.46.w1).
• Providing protection from sunlight is required to avoid the development of lesions if waterfowl are known to have consumed plants which may lead to Plant-Induced Photosensitisation (J5.19.w1, J5.22.w1).
• Waterfowl may not use man-made shelters even if these are available. When possible, plantings should be used to provide shelter (B96).
• Downy waterfowl being hand-reared or broody-reared must be provided with shelter from rain until they are fully-feathered, and they should have shade available (see: Rearing of Birds - Hand Rearing).

• In warm climates, appropriate shelter from the sun, and access to cooling breezes, should be provided to avoid hyperthermia (see Hyperthermia - Sunstroke - Heatstroke in Waterfowl, Elephants and Bears), particularly for Ursus maritimus - Polar bear and other northern bear species (shade should be always available for all bears).
• In cold climates, shelter from cold and wet should be provided, and heating may be required, particularly for tropical bears, to avoid chilling (Chilling - Hypothermia (with special reference to Waterfowl, Hedgehogs and Bears)).
• Young cubs not provided with an appropriately warm environment are particularly prone to Chilling - Hypothermia.

• Provision of shade is important in the prevention of Sunstroke / Heatstroke in lagomorphs.

• Provision of shade is important in the prevention of Sunstroke / Heatstroke in ferrets.

• As with all species, shelter from extremes of temperature, wind and rain should be freely available, also shade from direct sunlight. (V.w5)

• Accommodation Design for Mammals - Furnishings / Plantings
• Accommodation Design for Mammals - Housing / Denning Facilities

• A variety of man-made objects including fences, windows, power lines, power poles and telephone wires may be directly hazardous for wildlife which may fly or run into these objects or try to make use of them e.g. for perching or nesting.
• Power poles may be made safer for large species of birds which use them for perching or nesting by increasing the distance between earth and live wires such that they are no longer within wingspan of the birds.
• Power lines and telephone cables which are on known flight paths may be re-sited or may be made more visible by applying markers which may be seen more easily by the birds, thereby reducing the risk of collisions. Deaths due to electrocution may be decreased by increasing the distance between live and earth wires.
• Fences and windows may also be made more visible by markings to avoid traumatic injuries due to animals running/flying into them. Various means of increasing visibility include the application of e.g. predator silhouettes, white-washing windows and tying ribbons to fencing.
• Solid netting (e.g. tennis-court netting), sacking or other screening materials may be used to avoid abrasive trauma to plumage, fur or skin caused by individuals pacing up and down against, or trying to get out through, fencing or wire of cages.
• It is important to ensure that enclosures are safe for both the animals living in them and the keepers caring for them, not including any sharp corners, areas where an animal could become trapped or entangled, nails or other sharp points or edges which can cause injury, toxic plants, other poisons, etc. which could be hazardous to the animals. They should provide sufficient flight distance, hiding places and safe substrates if the animal runs.

(B14, B36.50.w50, B127, B469.3.w3, V.w5).

• Marking or removal of power lines and telephone lines on known flight paths for waterfowl is particularly important in reducing impact injuries (Impact Injury) and deaths by electrocution (Electrocution). In botulism-prone areas, there is the added importance of avoiding bird-kills from collisions or electrocution as the carcasses may act as substrate for Clostridium botulinum growth (see: Avian Botulism) (J48.69.w2, B20.14.w11, B37.x.w1, B127).
• Vegetation or screens may be used prevent visual contact between pairs of aggressive waterfowl in adjoining pens and therefore decrease aggressive interactions in which birds may damage themselves on netting (B29).

• Road traffic accidents are a common cause of mortality in wild bears in some areas and a less frequent cause of mortality in other areas. (B419.14.w14, J1.41.w4)
• Bear deaths from vehicle collisions may be reduced by placing warning signs in areas where bears cross roads, erecting fences along major highways, and building underpasses for bears to use. (B419.14.w14)

• It is essential to ensure that the house and garden are free of hazards when a rabbit has access to these. See: Mammal Behavioural Requirements - Enclosure Modification and Furnishings to meet Behavioural Requirements

• It is essential to ensure that areas of the house to which the ferret has access are free of hazards such as electrical cables and edible (to ferrets) foam or rubber furnishings or toys. 
  • See: Mammal Behavioural Requirements - Enclosure Modification and Furnishings to meet Behavioural Requirements

• There should be no sharp edges in primate housing (or on enrichment items) which might cause lacerations or punctures in accommodation for nonhuman primates. (B644.5.w5, D428.w2, V.w5)
• Care should be taken that the size of openings between bars or in wire mesh does not allow a limb to be put through and possibly be unable to be withdrawn. This can easily happen particularly with juveniles trying to access bits of food on the other side of a barrier. (B644.5.w5)

• Accommodation Design for Mammals (Mammal Husbandry and Management) - General, Substrate, Furnishings / Plantings
• Mammal Behavioural Requirements - Enclosure Modification and Furnishings to meet Behavioural Requirements

• Fencing may be used to prevent access of both wild and captive animals to an area containing a known hazard such as a toxin, or a habitat known to contain intermediate hosts (e.g. fencing off Lymnea snail habitat, for prevention of liver fluke (Fascioliasis)) in domestic animals (B46, B78)).
• Fencing may also be used to prevent contact between infected and non-infected animals, and thereby transmission of infectious disease. Where close contact between animals is required for disease transmission, double fencing may be used, a sufficient distance apart to prevent the animals from touching or closely approaching one another.
• For arthropod-borne diseases, a much greater distance between fences may be required to produce a gap over which the arthropods are unable to cross; this is likely to be impractical in most circumstances. However, fine-mesh screens may be used to deny arthropod disease vectors access to potential hosts in captive situations.
• N.B. There are often serious practical difficulties related to construction, maintenance and detrimental effects on e.g. migration which severely limit the use of fencing to prevent contact between populations of wild animals (e.g. infected and uninfected populations).

(B15, B36, B46, B78, B127)

• Fencing off areas is of limited use for preventing access of birds which can fly. However, fencing has been used successfully to deny access of waterfowl such as Branta canadensis - Canada goose to e.g. areas of recent plantings and might be used similarly to discourage waterfowl from entering a hazardous area.
• N.B. factors which may affect the effectiveness of fencing include the colour of the materials used: in keeping Branta canadensis - Canada goose from an area of new plantings, bright orange plastic netting was found to be more effective as a deterrent than otherwise-identical green netting (V.w1).
• The effectiveness of fencing (which waterfowl can normally fly over, if sufficiently motivated) also may vary depending on factors such as the attractiveness of the site to which access is being restricted and the alternative availability of equivalent resources (e.g. feeding ground, safe nesting sites).

(P12.10.w1:- The Management of Problems caused by Canada Geese - A Guide to Best Practice, P12.11.w2:- Integrated Management of Urban Canada Geese, V.w1, V.w5)

• Physical barriers, including e.g. netting over problem areas, may be used to prevent access of waterfowl (and other birds) to sites known to be heavily contaminated with toxins; this is less practical where larger areas are involved.
• Juvenile captive waterfowl may have their access blocked to water areas known to contain large numbers of nasal leeches blocked (see: Leech Infection).
• In areas where Leucocytozoonosis is known to be a problem, fine-mesh screens may be used to prevent the blackfly vectors, Simulium spp. from reaching ducklings and goslings.

(B15, B36, B127)

• Fencing or electric fencing can be used to keep rabbits and other lagomorphs out of an area. See information provided in Management of Unwanted or Illegally Held Animals - Pest Populations or Overabundant Animals

• Solid barriers, rather than mesh, are recommended for partitions between enclosures, since mesh does not prevent visual contact and may not depending on the size of the mesh) prevent physical contact. (D386.5.1.w5a)
• Solid barriers (including glass) between great apes and members of the public reduces the risk of transmission of pathogens in either direction. (P131.w10)

• Accommodation Design for Mammals - Perimeter Fences / Barriers
• Management of Unwanted or Illegally Held Animals - Pest Populations or Overabundant Animals

• Hazing or scaring may be used to keep or disperse animals from a localized disease agent. This may be most useful in the control of non-infectious diseases, for which dispersal of animals does not involve an attendant risk of dispersing the causative agent and re-locating the disease outbreak, and is most likely to be effective for localized problems.
• A variety of hazing methods may be used to disperse animals from an area, generally involving disturbance by means of moving vehicles, noise-makers, visual deterrents (e.g. scarecrows) or combinations of these.
• N.B.

• The effectiveness of different hazing methods, and of hazing at all is highly species dependent.
• Hazing, by whatever method, generally is effective only short-term.
• A longer-term effect may be possible if hazing is used in association with other management actions, such as decreasing the attractiveness of the local habitat, to encourage dispersal, and/or providing alternative attractive habitat (see: Relocation, below).

• Dispersion may be encouraged by decreasing the attractiveness of habitat to the species involved. This may involve reducing feed, shelter, nesting sites etc.
• Chemical repellents which harmlessly repel animals from areas are under development.

(B36.4.w4, B127, D10, P12.10.w1)

• Hazing may be used e.g. to keep waterfowl (and other species) from an area affected by oil (Oiling), an area of known to be heavily contaminated with lead shot (Lead Poisoning), or pesticide-treated fields (e.g. Organochlorine Toxicity), as well as to drive the birds from e.g. highly saline lakes where they might become trapped by Salt (Salt Encrustation). (Hazing may also be used to keep waterfowl away from an area where they are a nuisance, such as geese from grazing agricultural crops and fish-eating ducks from fishing areas or mussel-growing sites: See: Population Control - Scaring / Hazing).
• A variety of techniques have been used to haze waterfowl:

• Aircraft
• Boats
• Land vehicles, e.g. all-terrain vehicles (ATV), snowmobiles.
• Visual - Scarecrows, predator models, lights, balloons, flags, ribbons.
• Noise-makers - e.g. propane cannon, Breco buoy, Marine wailer
• Pyrotechnics (combined explosion, light and whistling noise)
• N.B.

• Hazing may be an important part of disease control particularly in keeping birds from known areas of contamination. Although costs associated with hazing can be considerable, they may ultimately be much lower that the cost of rescuing and treating diseased birds; particularly with oil spills (Oiling).
• Combining different methods (e.g. visual hazing techniques and noise-makers) may increase the effectiveness of hazing as no single method used to date is ideally effective.
• Effectiveness of hazing, by whatever method, may be increased by using hazing alongside actions to attract waterfowl to alternative, safe, locations, and by decreasing the attractiveness of the area to waterfowl.
• Timing of hazing may affect the effectiveness - e.g. scaring actions to remove nuisance birds from sites may be most effective if carried out in the early morning.

• Decreasing the attractiveness of an area to waterfowl may involve e.g.

• Draining wetland areas, as has been used in control of Avian Cholera outbreaks (B36.7.w7)
• Reducing food availability, including feeding by the public and reducing marginal vegetation
• Use of visual barriers between water and grazing areas, to deter geese
• Making banks steeper.
• Use of chemical repellents such as methyl anthralinate.

• Appropriate methods may vary depending on factors such as the location, feasibility and cost.

B36.4.w4, B36.42.w42, B36.47.w47, B127, P10.62.w1, P12.10.w1:- The Management of Problems caused by Canada Geese - A Guide to Best Practice, P12.11.w2:- Integrated Management of Urban Canada Geese, D10, D13).

• P12.10.w1:- The Management of Problems caused by Canada Geese - A Guide to Best Practice
• P12.11.w2:- Integrated Management of Urban Canada Geese
• Hazing - Aircraft
• Hazing - Biosonics
• Hazing - Boats
• Hazing - Electronic Sound Generators
• Hazing - Land Vehicles
• Hazing - Lasers
• Hazing - Propane Cannon
• Hazing - Pyrotechnics
• Hazing - Scarecrows etc.
• Hazing - Trained Raptors

• Animals may be encouraged to concentrate in an area by providing an attractive area of habitat for the animals.
• This may involve provision of feed in an area, or production or development of habitat attractive to the species of concern, including preventing disturbance by hunting or other human activity.
• Relocation may also involve similar activities, often in conjunction with dispersal/hazing actions at a site the animals are being encouraged to move from, and/or trapping and moving.
• In encouraging use of a particular area it is important to consider possible hazards associated with the proposed management activities: food provided must be checked to ensure it is not mouldy, the possibility of the development of botulism (Avian Botulism) should be considered before flooding an area and the risk of disease due to excessive concentration of the population at the site must be addressed.
• Concentration of animals in a limited area, for example by providing food, may also be used for capture and euthanasia or for testing and selective culling (see below: Depopulation).

(B36, B127)

• New habitat has been created, and hunting suspended, to provide alternate habitat for ducks being dispersed by hazing away from a botulism-prone area (Avian Botulism) (B127).
• Creation of new habitat has been used along with drainage of the area affected by the outbreak in the control of Avian Cholera (B36.7.w7).
• Creation of a refuge area, by prohibiting hunting in the area, has been used to hold infected geese in the refuge area as part of a control effort in an Avian Cholera outbreak (B36.7.w7).
• Trapping of moulting (therefore flightless) individuals and moving to a new site has been used in the past to reduce Branta canadensis - Canada goose populations on sites in the UK and the USA. Problems with this practice for reducing population density include geese returning to their original site once able to fly again, and expansion of population in the new areas, as well as rapid re-expansion of the population at the original site by natural recruitment (P10.62.w1, P12.10.w1:- The Management of Problems caused by Canada Geese - A Guide to Best Practice).

• P12.10.w1:- The Management of Problems caused by Canada Geese - A Guide to Best Practice

• Depopulation may be appropriate for use in the case of a localized infectious disease problem.
• Depopulation is commonly used as part of disease prevention programmes in intensive farming such as poultry, with "all-in, all-out" systems, in which all animals are taken from a building or site and the site is not re-populated until it has been cleaned, disinfected and a certain length of time has elapsed.
• An intensive effort is required for depopulation. Depopulation operations on wild animal populations are usually effective for only a limited time, as new individuals will usually move into the vacant habitat.
• General depopulation over a large area has been used e.g. in killing deer to control an outbreak of foot-and-mouth disease in California.
• Selective depopulation, in which only animals which are carrying the disease are removed from the population is most useful if it is easy to detect diseased/carrier individuals.
• Separation and sometimes removal of diseased individuals is routine in the management of captive wild animals (See also Preventative Medicine for Mammals - Quarantine, Hygiene and Disinfection). 
• Selective depopulation is usually impractical for wild animals due to requirement for capture and holding of the population during the period of testing.
• Barrier Zone depopulation, in which animals are removed in an area around a disease outbreak may be used to prevent a disease spreading to animals outside the barrier zone. This has been used in e.g. the control of rabies and rinderpest.

(B32.1.w34, B126, B127)

• Depopulation has been recommended for the control of Duck Plague particularly due to the risks of survivors acting as carriers and infecting new birds (B36.16.w16).
• Depopulation of American coots, gulls, terns and eiders has been used in the control of an Avian Cholera outbreak. It has been suggested that destruction of migratory birds infected with this disease could only be justified in special circumstances and conditions:

"(1) The outbreak must be discreet and localized rather than generalized and widespread;
(2) Techniques must be available that will allow complete eradication without causing widespread dispersal of potentially infected birds;
(3) The methods used must be specific for target species and pose no significant risk for non-target species;
(4) Eradication must be justified on the basis of risk to other populations if the outbreak is allowed to continue; and
(5) The outbreak represents a new geographic extension of avian cholera into an important migratory bird population." (B36.7.w7).

• Selective depopulation of carriers may be used e.g. to control Salmonella infection in a flock (detecting carriers by repeated fecal cultures) (B36.9.w9)

• Depopulation is sometimes used in the control of infectious disease in commercial rabbit populations, for example this has been used in the control of viral haemorrhagic disease (Rabbit Haemorrhagic Disease). (B22.30.w17, J64.10.w7, J83.31.w4)

• Depopulation may be considered in the control of highly infectious diseases in laboratory or breeding colonies. For example, if an outbreak of Canine Distemper occurs in a ferret colony, depopulation (euthanasia of all ferrets) is recommended, with repopulation after disinfection. (J213.8.w3)
•  

• Preventative Medicine for Mammals - Quarantine, Hygiene and Disinfection

• Separation of diseased individuals from the rest of the group is routine in management of captive wild animals and quarantine is used routinely to prevent disease entering a collection of animals, by keeping new arrivals separate from the main collection (see: Preventative Medicine for Mammals - Quarantine, Hygiene and Disinfection).
• Quarantine is very important in the translocation of wild animals if important pathogens are not to be moved to new areas: such movement may be considered as a form of environmental contamination. Inevitably, animals carry with them a complex population of both internal and external macroparasites (arthropods, helminths) and micro-organisms. An appropriate quarantine period, with associated screening for both pathogenic micro-organisms and macroparasites, should be an integral part of any translocation programme.
• Diseases which are known to be present in the area from which the animal is being moved, but not known to be present in the area into which it is being translocated are of particular concern.
• Effective quarantine includes:

• A sufficient length of time for diseases to become clinically manifest and/or parasitic infections to become patent.
• Appropriate sample collection and testing.
• Repeated sampling e.g. of faeces for bacteria and parasites which may be shed only intermittently or after a prepatent period.
• Appropriate action if an animal is found to be carrying an important pathogen or parasite. This may include treatment of the individual and/or group, or rejection of the animals for translocation.

(J57.10.w1, B127)

• A period of quarantine is recommended for waterfowl entering a collection. The period suggested varies from 3 weeks to 60 days. (B11.33.w1, B13.2.w21, B96.w2)

• Quarantine should be carried out for a minimum of 30 days. (B23.4.w13, B433)
  • Quarantine of bears from a rabies area may be increased to six months. (B433)
• Quarantine, testing for external and internal parasites, and treatment for parasites while in quarantine, is particularly important to prevent contamination of enclosures or wild habitats with parasites which are difficult to eliminate. (B407.w18, B433)
• Suggested testing while the bear is in quarantine is provided in Preventative Medicine for Mammals - Quarantine, Hygiene and Disinfection

• All primates entering a collection, from whatever origin, should be quarantined for a period. During this time, appropriate screening tests can be carried out and vaccination reviewed. (D428..8.2.w8b)
  • A minimum period of 30 days is recommended when individuals move from an approved premises. A shorter period may be possible from a facility with a clean health record and no imports within the previous year, but screening tests should still be carried out. (D428.8.2.w8b)
  • Longer periods are needed for individuals arriving from the wild or from non-approved premises. (D428.8.2.w8b)
  • Prior to a move, the individual's health records should be sent to the receiving institution, together with details of any significant disease in primates in the originating collection within the past six months. (D428.8.2.w8b)

• Preventative Medicine for Birds - Quarantine, Hygiene and Disinfection
• Preventative Medicine for Mammals - Quarantine, Hygiene and Disinfection

"A high density of population ... must be set down as the most fundamental condition favourable to disease." Leopold, 1933 (B126).

• High population density is recognized to increase the rate of transmission of contagious diseases and to increase the environmental build up of e.g. protozoal oocysts and infective stages of gastrointestinal helminths. For toxic diseases high population density may increase the number of birds exposed to the toxin.
• In some cases the overall area available for the population may be adequate, but local overcrowding occurs at sites where food, water or resting sites are available/provided. The high population density at such sites, with, for example, associated high levels of faecal contamination, may produce conditions highly conducive to the development of disease.
• Population density may be decreased by either decreasing the population (culling) or increasing the area available for use by the population (habitat creation, translocation).
• In general, increasing the area available is preferable, but this may not always be possible in practice.
• In the case of local overcrowding at feed, water or resting areas, the provision of multiple sites fulfilling each of these requirements may have a considerable impact on the level of disease.
• N.B. decreasing population density by decreasing the population e.g. by culling is likely to be effective only in the short term, as new individuals are usually recruited into the population by reproduction and/ or immigration from other areas.
• Longer-term reduction of population density in an area might be possible by controlling reproductive output.

(B36, B126, B127, Th3)

• Within collections, it is important to avoid overstocking the area available, and to decrease population density if overstocking becomes apparent (e.g. excessive poaching of ground, overgrazing). Waterfowl should not be bred if there is neither sufficient space in which to keep them nor a reasonable expectation that alternative accommodation will be available (V.w5).
• Reduce stocking levels may be important in the control of diseases such as Salmonellosis (B11.40.w8).
• For wild waterfowl, it may be possible to increase the area available, for example by flooding an area to provide extra habitat, and by general habitat management to avoid habitat degradation (B36.27.w27).
• Reducing population density may be very important in the control of infectious diseases such as Avian Cholera in wild waterfowl (B36.7.w7).

• Lacerations & Punctures, including bite wounds
• Unspecified skin conditions of Bears

• P12.10.w1:- The Management of Problems caused by Canada Geese - A Guide to Best Practice
• Accommodation Design for Mammals - Behavioural and Breeding Considerations
• Mammal Behavioural Requirements - Group Composition and Breeding Requirements

• Inadequate or incorrect nutrition not only may lead to specific nutritional deficiency / nutrient excess diseases but also may considerably reduce resistance to other disease agents.
• Environmental management to ensure adequate nutrition may range from direct provision of feed to management of grass swards for grazing, deliberate planting of food crops for wildlife and snow clearance to increase food availability in winter.
• Avoiding over-population, and population reduction if necessary, may be a part of nutritional management, to ensure sufficient food availability for the population.
• Supplementation of specific nutrients (e.g. protein, trace elements) and correction of inappropriate diets may be important as well as a general increase in nutritional levels.

(J56.19.w1, B36.51.w51, B46, B78, B126, B127, B131.w2, B429.10.w10)

• Vitamin A Deficiency is recognized as a risk factor in the development of Bumblefoot.
• Poor nutrition is recognized to interact with gastrointestinal parasitism in waterfowl.
• A variety of specific deficiencies and nutrient imbalances are important in the development of problems such as Angel Wing, Perosis, Gout etc. as well as specific nutritional diseases (See: Food and Feeding for Birds -General, and List of Micro-nutrient (Vitamin / Mineral) Diseases).

(B15, B35.13.w6, B36.32.w32, V.w5)

• Susceptibility to skin diseases, particularly in Ursus maritimus - Polar bears, may be linked to vitamin A deficiency; see Vitamin A-responsive Skin Disease in Bears.
• Calcium-Vitamin D Metabolism Imbalance has been seen in bears.
• Excess feeding of captive bears can lead to Obesity in Bears.
• Bears should not be fed meat from pigs (swine) due to the risk of their becoming infected with Trichinella (see: Trichinella Infection in Hedgehogs and Bears) and due to the risk of Aujeszky's disease (see: Pseudorabies in Bears)

• The ideal diet for lagomorphs is based on the wild diet. In practice, this means access to grass and other natural vegetation for grazing, if possible, and basing the diet on hay with some other green foods and minimal concentrates otherwise.
• Laboratory and commercial rabbits are commonly fed solely or mainly a balanced pelleted diet.
• Appropriate nutrition is important for prevention of deficiency diseases, dental disease and some gastro-intestinal diseases. See: Food and Feeding for Mammals (Mammal Husbandry and Management)

• While nutritional diseases are uncommon in ferrets, they do occur, particularly in farmed ferrets but also occasionally in other situations. Appropriate nutrition is important for the prevention and management of nutritional diseases including Nutritional Steatitis in Ferrets, Thiamine Deficiency in Waterfowl, Hedgehogs and Ferrets and Nutritional Hyperparathyroidism in Ferrets.

• Changing the infant milk formula used was effective in treating hand-reared infants suffering from Specific Protein Intolerance in a Bonobo. (B338.18.w18, R1.21Oct2008.w1)

• Food and Feeding for Mammals (Mammal Husbandry and Management)
• Hand-rearing of Orphaned Wildlife (with special reference to UK Wildlife)
• Wildlife Casualty & Convalescent Feeding (with special reference to UK Wildlife)